The present invention relates to an electronic control apparatus accommodating a circuit board in an internal protection space of a housing of the electronic control apparatus.
An electronic control apparatus mounted in a vehicle, such as an engine control unit and a control unit for automatic transmission generally includes a housing formed by combining a plurality of housing members with each other. An internal protection space (i.e., a space having a waterproof property and the like) of the housing accommodates a circuit board on which electronic components are mounted. These electronic components include electronic components such as a condenser, and heat-generating electronic components such as an arithmetic processing unit (CPU) and a semiconductor switching element which generate heat based on those actions.
In such a case, the heat-generating electronic component itself and an opposite-surface portion of the circuit board which corresponds to a location of the heat-generating electronic component are heated. In order to suppress a temperature increase of this heated portion (especially, the electronic component), a structure is conceivable in which a heat of the heated portion is transferred to an inner wall surface of the housing member and then is radiated through an outer wall surface of the housing member into the atmosphere. U.S. Patent Application Publication No. 2003/0184969 corresponding to the family Japanese Patent Application Publication No. 2003-289191 discloses a previously proposed electronic control apparatus. In this technique, a convex portion protrudes from a portion of an inner wall surface of a housing which is opposed to the heated portion of the circuit board. This convex portion is close to the heated portion through a clearance.